Ball valve members have long been in use especially in the field of gas and water distribution systems. In general, ball valve members have included a housing having an opening through which an operating stem is inserted to engage a surface slot or groove formed in a ball of the type having a through bore for movement into and out of alignment with conduits connected to the housing of the ball valve member. Internal seals engage the arcuate surface of the ball valve member to provide a secure seal over the life of the valve. However, it frequently happens that due to debris accumulating in and about the seals in the ball valve member, frozen liquid or the like, difficulty in rotating the ball valve through the operating stem engaged therewith has resulted in disconnection or breakage of the stem or the portion of the stem engaged in a slot formed in the surface of the ball valve.
While a number of attempted solutions have been proposed to increase the strength of the ball-stem connection, many of these have been relatively expensive to employ in a mass production facility or have proved impractical to adapt to a valve housing that has been prescribed by regulatory authorities.
In the past, the formation of the receiving slots in the surface of a ball valve member has been effected by use of a milling tool such as a key slot cutter or an end mill tool which is indexed to cut across the body of the ball valve to form a recess for cooperation with the tip of an operating stem. This was a time-consuming and labor-intensive operation which significantly contributed to the cost of the individual ball valve members.
With the operation of the present invention, the cost of manufacturing the ball valve for ready cooperation with an operating stem will be significantly reduced while significantly increasing the strength of the connection once effected.
The present invention provides an improved method of forming a ball valve member with a receiving slot whereby a connection with an operating stem can be effected that will be a stronger ball-stem connection yet less expensive than those connections utilized previously. In addition, a flow indicating feature is provided whereby a user will be readily able to determine the oriented condition of the ball valve member in establishing a connection with a stem either at the factory or in the field in an established fluid distribution system.
In a preferred embodiment, a cutting tool of the type having first and second annular cutting surfaces is employed where one of the annular surfaces has a reduced diameter relative to the other of the cutting surfaces. In carrying out the method of the present invention, the cutting tool is oriented generally perpendicularly to the through bore of the ball valve member and then is moved transversely to the ball valve surface to commence cutting a slot which has a longitudinal axis that extends perpendicular or parallel to the axis of the through bore. Cutting is continued until the second cutting surface which has a smaller radius than the first cutting surface engages and cuts a small recess adjacent to the slot for the operating stem. In some constructions, this will permit the main or first cutting surface to cut entirely through the thickness of the ball valve member to form an opening to the through bore of the ball valve but will always allow deeper penetration of the cutter than with the standard single cutter diameter.
With this arrangement, a much deeper penetration with a smaller diameter cutter of the ball member by the operating stem can be effected with a smaller diameter cutter, thus greatly increasing the strength of the connection between the operating stem and the ball valve member.
The foregoing and other advantages of this invention will become apparent to those skilled in this art as consideration is given to the following detailed description taken in conjunction with the accompanying drawings in which: